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Review reviewHigh

CVE-2025-40026

Linux

In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Don't (re)check L1 intercepts when completing userspace I/O When completing emulation of instruction that generated a userspace exit for I/O, don't recheck L1 intercepts as KVM has already finished that phase of instruction execution, i.e. has already committed to allowing L2 to perform I/O. If L1 (or host userspace) modifies the I/O permission bitmaps during the exit to userspace, KVM will treat the access as being intercepted despite already having emulated the I/O access. Pivot on EMULTYPE_NO_DECODE to detect t...

CVSS
7.9
EPSS
-
- percentile
CISA KEV
Not listed
Published
2025.10.28
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability-
Technical severityCVSS 7.9

Vulnerability overview

In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Don't (re)check L1 intercepts when completing userspace I/O When completing emulation of instruction that generated a userspace exit for I/O, don't recheck L1 intercepts as KVM has already finished that phase of instruction execution, i.e. has already committed to allowing L2 to perform I/O. If L1 (or host userspace) modifies the I/O permission bitmaps during the exit to userspace, KVM will treat the access as being intercepted despite already having emulated the I/O access. Pivot on EMULTYPE_NO_DECODE to detect t...

Affected product and versions

Product
Linux
Affected versions
>= 8a76d7f25f8f24fc5a328c8e15e4a7313cf141b9 < a908eca437789589dd4624da428614c1275064dc, >= 8a76d7f25f8f24fc5a328c8e15e4a7313cf141b9 < 00338255bb1f422642fb2798ebe92e93b6e4209b, >= 8a76d7f25f8f24fc5a328c8e15e4a7313cf141b9 < e0ce3ed1048a47986d15aef1a98ebda25560d257, >= 8a76d7f25f8f24fc5a328c8e15e4a7313cf141b9 < ba35a5d775799ce5ad60230be97336f2fefd518e, >= 8a76d7f25f8f24fc5a328c8e15e4a7313cf141b9 < 3d3abf3f7e8b1abb082070a343de82d7efc80523, >= 8a76d7f25f8f24fc5a328c8e15e4a7313cf141b9 < e7177c7e32cb806f348387b7f4faafd4a5b32054, >= 8a76d7f25f8f24fc5a328c8e15e4a7313cf141b9 < 3a062a5c55adc5507600b9ae6d911e247e2f1d6e, >= 8a76d7f25f8f24fc5a328c8e15e4a7313cf141b9 < 7366830642505683bbe905a2ba5d18d6e4b512b8, >= 8a76d7f25f8f24fc5a328c8e15e4a7313cf141b9 < e750f85391286a4c8100275516973324b621a269, >= 3.0
Fixed versions
No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Linux and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:H
CWE
Not available